The invention relates to an adjusting device for a rotary body, in particular for a fan of a cooling blower of an internal combustion engine, or a shaft or a rotor of an electric motor. The invention also relates to a rotary body, in particular a fan, a shaft or a rotor.
Dynamic imbalances arise when an axis of rotation of a component or rotary body no longer coincides with one of the stable main axes of inertia of the component. It is prior art for fans for cooling an internal combustion engine and other rotating components, such as for example motor armatures, drivers and rotors, to be geometrically designed so as to generate the least possible dynamic imbalance while adhering to specified dimensions. Real component geometries however exhibit dimensional and position errors with respect to an ideal, tolerance-free model, with the result that there is always a dynamic imbalance. To limit the maximum dynamic imbalance, components of cooling blowers must be produced with low dimensional and position tolerances. Furthermore, effects of the dynamic imbalance are often limited by means of cumbersome damping and/or decoupling measures.
A present complaint is high dynamic imbalances of cooling fans in motor vehicles, because these incite mechanical vibrations and can thereby cause noises, steering wheel vibration or possibly even rapid bearing wear in the blower motors. Said problem is intensified with increasing blower dimensions, in particular fan diameter, and noise sensitivity. Furthermore, there is an emerging trend in the automobile industry, motivated by the problem of minimizing CO2, for the weight reduction of vehicles to be expedited and for increasing use to be made of highly rigid, lightweight front ends and body fixtures without decoupling elements, damping elements or absorber masses. As a result, the transmission behavior of the mechanical vibrations (forces) caused by the dynamic imbalance into a passenger compartment is adversely affected; the described problem is intensified. Previous specifications provide dynamic imbalance limits which are still practicable, and which presently lie at a maximum of 25,000 g·mm2. Dynamic imbalance limits of a maximum of 1,500 to 2,000 g·mm2 will however be demanded in future. With the design concepts and production methods known today, such demands can no longer be expediently met in an economical manner, because either very high scrap rates are to be expected or the fans become too expensive.